Microencapsulated oil field chemicals

Details Microencapsulated oil field chemicals Microencapsulated oil field chemicals

1999-07-13

2001-12-04

Tucker, Philip (Department: 1712)

Earth boring, well treating, and oil field chemistry

Well treating

Contains organic component

C507S244000, C507S239000, C507S261000, C507S902000, C507S939000, C264S004300, C428S402200

Reexamination Certificate

active

06326335

ABSTRACT:

TECHNICAL FIELD
This invention relates to compositions and processes for treating oil wells.
BACKGROUND OF THE INVENTION
Conditions which adversely affect the production of oil from a well include: (1) the deposition of plugging materials brought out during production (e.g., formation of “scale”); and (2) corrosion of the well tubing and operating equipment in the well. Treatment of a well by introducing an oil field chemical can increase the rate of production, prolong the producing life, and lessen the deterioration of well equipment.
However, it is difficult to treat the individual wells which are widely dispersed geographically, which are inaccessible during operation, and which contain fluids of widely varying composition.
One moderately successful approach is disclosed in U.S. Pat. No. 3,676,363, Mosier, issued Jul. 11, 1972, said patent being incorporated herein by reference. The capsules disclosed therein are weighted. The capsules are deposited in the sump of a well where they slowly dissolve. Microencapsulation of various hydrophobic liquids is well known. Microcapsules have been suggested for encapsulation of perfumes, medicines, adhesives, dyestuffs, inks, etc.
SUMMARY OF THE INVENTION
It has now been discovered that the walls of microencapsulated oil field chemicals of the type described in U.S. Pat. No. 3,676,363, supra, said patent being incorporated herein by reference, are susceptible to damage, by many materials present in some ground waters, e.g., high brine contents and relatively large amounts of certain cations, and that, surprisingly, incorporation of strong chelating agent, like ethylenediaminetctraacetic acid, stabilizes the capsule wall so that extended release of the oil well chemical is possible.
DETAILED DESCRIPTION OF THE INVENTION
Strong Chelating Agent
The strong chelating agents are incorporated into the microcapsules herein by addition to either the aqueous solution or the water-immiscible solvent used to form the microcapsules as described hereinafter. Useful chelating agents include the acid forms of compounds known to complex heavy metals. Many such compounds are used in detergent compositions, typically as their salts.
Polycarboxylate materials useful herein, especially in the said preferred compositions, include the acid forms, or salts, of builders disclosed in U.S. Pat. No. 4,915,854, Mao et al., issued Apr. 10, 1990, and U.S. Pat. No. 4,704,233, Hartman and Perkins, issued Nov. 3, 1987, said patents being incorporated herein by reference. Suitable materials preferably have relatively strong binding constants for heavy metals under both acid and alkaline conditions. Preferred materials have the generic formula:
R
5
—[O—CH(COOH)CH(COOH)]
n
R
5
wherein each R
5
is selected from the group consisting of H and OH and n is a number from about 2 to about 3 on the average. Other preferred materials include the acids, and salts, described in the copending U.S. patent application Ser. No. 07/587,477 of Stephen Culshaw and Eddy Vos for “Hard-Surface Cleaning Compositions,” filed Sep. 19, 1990, said patent application being incorporated herein by reference.
In addition to the above materials, other materials include the acid forms of those disclosed in U.S. Pat. No. 4,769,172, Siklosi, issued Sep. 6, 1988, and incorporated herein by reference. Still others include the chelating agents having the formula:
wherein R is selected from the group consisting of:
—CH
2
CH
2
CH
2
OCH
3
; —C(CH
2
OH)
3
; and mixtures thereof.
Chemical names of the acid form of some of the suitable chelating agents herein include:
N(3-hydroxypropyl)imino-N,N-diacetic acid (3-HPIDA);
N(-2-hydroxypropyl)imino-N,N-diacetic acid (2-HPIDA);
N-glyeerylimino-N,N-diacetic acid (GLIDA);
dihydroxyisopropylimino-(N,N)-diacetic acid (DHPIDA);
methylimino-(N,N)-diacetic acid (MIDA);
2-methoxyethylimino-(N,N)-diacetic acid (MEIDA);
amidoiminodiacetic acid (also known as sodium amidonitrilotriaeetic, SAND);
cetamidoiminodiacetic acid (AIDA);
3-methoxypropylimino-N,N-diacetic acid (MEPIDA); and
tris(hydroxyrnethyl)methylimino-N,N-diacetic acid (TRIDA).
Methods of preparation of the iminodiacetic derivatives herein are disclosed in the following publications:
Japanese Laid Open publication 59-70652, for 3-HPIDA;
DE-OS-25 42 708, for 2-HPIDA and DHPIDA;
Chem. ZVESTI 34(1) p. 93-103 (1980), Mayer, Riecanska et al., publication of Mar. 26, 1979, for GLIDA;
C.A. 104(6)45062 d for MIDA; and
Biochemistry 5, p. 467 (1966) for AIDA.
Still other chelating agents comprise amino polycarboxylates like nitrilotiiacetic acid, ethylene diamine tetraacetic acid, polyethyleneamine polyacetic acids, etc.
The chelating agents of the invention are preferably present at levels of from about 2% to about 14% of the total composition, more preferably from about 3% to about 12%, even more preferably from about 5% to about 10%.
Preparation of Microcapsule
The microcapsules of this invention can be prepared by any procedure or variation thereof wherein an oil field chemical is dispersed in a water-immiscible solvent, and then emulsified with an aqueous solution containing one or more macro colloids which are capable of undergoing simple or complex coacervation. In the process of coacervation, one or more of the macro colloids deposits itself around the dispersed droplets of the water-immiscible solvent and treating agent. The droplets are thereby completely encapsulated and sealed. Various techniques for accomplishing such microencapsulation by coacervation are well known in the art, and provide the technical means for preparing the particular novel microcapsule compositions which can be used in practicing the method of the present invention. For example, there can be employed the encapsulation techniques described in U.S. Pat. No. 2,800,457 (Re. 24,899), Green et al.; U.S. Pat. No. 2,800,458, Green, issued Jul. 23, 1957; U.S. Pat. No. 3,159,585, Evans et al., issued Dec. 1, 1964; U.S. Pat. No. 3,533,958, Yurkowitz, issued Oct. 13, 1970; U.S. Pat. No. 3,697,437, Fogle et al., issued Oct. 10, 1972; U.S. Pat. No. 3,888,689, Maekawaet al., issued Jun. 10, 1975; Brit. Pat. 1,483,542, published Aug. 24, 1977; U.S. Pat. No. 3,996,156, Matsukawa et al., issued Dec. 7, 1976; U.S. Pat. No. 3,965,033, Matsukawa et al., issued Jun. 22, 1976; and U.S. Pat. No. 4,010,038, Iwasaki et al., issued Mar. 1, 1977, etc., all of said patents being incorporated herein by reference.
Other techniques and materials for forming microcapsules are disclosed in U.S. Pat. No. 4,016,098, Saeki et al., issued Apr. 5, 1977; U.S. Pat. No. 4,269,729, Maruyama et al., issued May 26, 1981; U.S. Pat. No. 4,303,548, Shimazaki et al., issued Dec. 1, 1981; U.S. Pat. No. 4,460,722, Igarashi et al., issued Jul. 17, 1984; and U.S. Pat. No. 4,610,927, Igarashi et al., issued Sep. 9, 1986, all of said patents being incorporated herein by reference.
These preferred procedures utilize a complex hydrophilic colloid material, such as gelatin, to encapsulate water-immiscible droplets of an oil-in-water type emulsion. Besides gelatin, other hydrophilic colloids can be used, including albumen, alginates such as sodium alginate, casein, agaragar, starch, pectins, carboxymethyl cellulose, Irish moss and gum arabic.
The wall materials are those typically used to form microcapsules by coacervation techniques. The materials are described in detail in the following patents incorporated herein by reference, e.g., U.S. Pat. Nos. 2,800,458; 3,159,585; 3,533,958; 3,697,437; 3,888,689; 3,996,156; 3,965,033; 4,010,038; and 4,016,098. The preferred encapsulating material is gelatin, either precipitated by a salt, e.g., sodium sulfate or ammonium sulfate, or coacervated with a polyanion such as gum arabic and more preferably cross-linked with a cross-linking material such as formaldehyde or glutaraldehyde.
Preferred gelatin is Type A (acid precursor), preferably having a Bloom strength of 300 or, less preferably, 275, then by increments of 25, down to the least preferred 150.
Simple coacervation can be accomplished as described in U.S. Pat. Nos. 2,800,457, Green et al.;

Affiliated with

Also associated with

Rating

Microencapsulated oil field chemicals does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Microencapsulated oil field chemicals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microencapsulated oil field chemicals will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2572065